1. Field of the Invention
The present invention relates to wheel assemblies for in-line skates. More particularly, the present invention is related to the hub structure of a wheel assembly and how the hub structure effects the performance of the surrounding wheel.
2. Description of the Prior Art
In recent years in-line skates have become increasingly popular. There now exist many professional and semi-professional sport activities where the players wear in-line skates. For example, there are roller hockey leagues, speed skating competitions and the like.
Like with many different sports, when the athletic abilities of different competitors are evenly matched, it is often the quality of that player's equipment that determines who will win and who will loose the competition. In sports that use in-line skates, it is commonly the quality of the skate that mostly effects the performance of the athlete.
One of the most important features of an in-line skate is the wheel assembly. The wheel assembly is comprised of a hub that spins on an axle and the wheel that is molded onto the hub. The wheel is the portion of the skate that actually contacts the ground. In order to preform well, the material of a wheel must embody two characteristics. First, the wheel must be able to grip the ground when a person is turning or stopping, thereby optimizing control. Secondly, the material of the wheel must minimize the drag of friction against the ground when a person is skating straight, thereby optimizing speed. The ability of the wheel to grip the ground when turning, yet be of low friction when skating straight are diametrically opposed properties. Consequently, most every wheel assembly design selects a compromise where neither speed nor control are optimized.
In the prior art, a common method of changing the performance of a wheel is to alter the composition of the material of the wheel. If a soft material were used in the manufacture of the wheel, the wheel would grip the ground well and the ability of the wheel to turn and stop would be greatly enhanced. However, soft materials typically do not wear well. Furthermore, the soft material would significantly slow the speed of the skates. If a hard material were used in the manufacture of the wheel, the wheel would have a low coefficient of friction and would wear well. However, the wheel would have a tendency to slide along the ground when a person tried to turn sharply or stop. It is for these reasons that most in-line skates used a medium hardness plastic composition for molding the wheels. A medium hardness plastic wheel have an average wear life, an average ability to turn and an average speed capacity.
In an attempt to optimize performance, wheel assembly designers have altered the shape of the hub in the center of a wheel assembly so that the hub shape effects the performance of the wheel. In such prior art designs, a relatively soft material is used in the manufacture of the wheel. However, the hub is designed to extend into the material of the wheel and limit the deflection of the wheel. As a result, the soft material provides good turning ability, while the hub prevents excessive deformation of the wheel and allows for greater speed. Such prior art wheel assemblies are exemplified by U.S. Pat. No. 5,320,418 to Chen, entitled Skate Wheel Structure, and U.S. Pat. No. 5,573,309 to Bekessy, entitled In-Line Roller Skate Wheel Assembly. Such prior art designs do improve the performance of the wheel assembly, however, both speed and turn performance are still greatly compromised.
A need therefore exists in the art for a wheel assembly for an in-line skate that comes closer to optimizing both speed and turning performance. This need is met by the present invention as described and claimed below.